Living World - Cold Characteristics

The physical characteristics of a cold environment.

Polar - The regions of Earth surrounding the North and South Poles. These regions are dominated by Earth's polar ice caps, the northern resting on the Arctic Ocean and the southern on the continent of Antarctica.

Tundra - The flat, treeless Arctic regions of Europe, Asia and North America, where the ground is permanently frozen. Lichen, moss, grasses and dwarf shrubs can grow here.

A large amount of our globe is classified as cold environments. Cold environments cover over 25% of the World's land surface and are incredibly varied in their nature. Defining cold environments is therefore difficult because of the variety of cold environments. In Britain, parts of Northern and upland Scotland are cold environments for at least part of the year and there is regular snow cover in winter in Aviemore.
One of the main controlling factors of how cold a place is and what cold features an area has is LATITUDE. At extreme latitudes, there are Ice sheets in areas of extreme cold such as Antarctica, which can be over 2000m in depth and which cover almost the entire continent. In the Northern Hemisphere no such large continental land mass exists at the North Pole, so the Arctic is composed of sea ice, which changes in thickness and extent from month to month and year to year.

Cold environments often occur where cold sinking air creates freezing winds and at the highest latitudes, the sun might not rise for many months of the year. These are difficult places to live, but many people do live inside the Arctic Circle. The small settlement of Alert, in the Qikiqtaaluk Region, Nunavut, Canada, is the northernmost permanently inhabited place in the world, at latitude 82°north, just 817 kilometres (508 mi) from the North Pole.

Polar and Tundra environmentsPolar environments
These are the world’s coldest places and are found within 66.5°N (the Arctic Circle) and the North Pole, and 66.5°S (the Antarctic Circle) and the South pole.
These include Greenland, Siberia, Northern Canada and parts of Northern Europe in the North, and Antarctica in the South.
They are characterised by barren landscapes, glaciers and huge ice sheets.
The average monthly temperature is always below 0°C which allows snow and ice to accumulate despite low precipitation levels.
Polar areas are covered in ice with some ice-free areas called Nunataks.

Tundra environments
These areas are found to the south of ice caps in the northern hemisphere. The word comes from the Sami (northern Finland), and the original word tūndâr means "uplands" and "treeless mountain tract”
Tundra areas cover approximately 1/5 of the world’s land surface, including parts of Northern Canada and Russia.
The land is not permanently covered in ice, but does get snow covered every year and gets very cold winter temperatures.
Much of the ground is permafrost – ground that is permanently frozen, but the surface will thaw in summer. The layer that thaws at the surface is known as the active layer. Around a quarter of the Earth’s land surface is affected by some type of permafrost. The plants that can survive here are therefore low lying, such as shrubs, mosses and lichens.
These plants allow for biodiversity, at a low level. Animals found in the Arctic include musk ox, polar bears, arctic fox and caribou.

High Mountain areas (Alpine)
Temperature decreases with height through our atmosphere. For every 100m we ascend, temperature drops on average 0.6°C, so many mountainous areas also qualify as cold environments. This means that at lower altitudes they have features of tundra environments and Arctic areas at higher altitudes.

Tundra climates

The climate graph above shows the temperature and precipitation for the town of Old Crow, in Yukon, Northern Canada. The temperature is above freezing for just 5 months of the year and the thermal growing season is just 3 months a year. These conditions make it difficult for plant growth, and subsequently make it difficult for animal life to find food. Coupled with this, there will be permanent darkness in winter and 24hours of sunlight at the height of summer.
The tundra climate is very harsh in winter, the precipitation falls as snow and although the average temperatures are -25°C in some months the daily minimum can be much lower, dropping below -40°C. Soils also freeze during these months, making life for most plants during this time impossible.

Polar climates
The climate graph below shows the climate for McMurdo Research station in Antarctica, which is an American research station on the South tip of Ross Island. This area is classed as a cold desert, there is very little precipitation as the air cannot hold much water vapour as it is so cold. The precipitation that does fall does so as snow and ice. Average temperatures are always below freezing point, but daytime summer temperatures can exceed 0°C.